https://git.gnupg.org/cgi-bin/gitweb.cgi?p=libgpg-error.git;a=patch;h=791177de023574223eddf7288eb7c5a0721ac623

From 791177de023574223eddf7288eb7c5a0721ac623 Mon Sep 17 00:00:00 2001
From: Werner Koch <wk@gnupg.org>
Date: Sun, 18 Mar 2018 17:39:43 +0100
Subject: [PATCH] core: Fix regression on arm64 due to invalid use of va_list.

* src/logging.c (_gpgrt_log_printhex): Provide a dummy arg instead of
NULL.
--

Fix
Suggested-by: Jakub Wilk <jwilk@jwilk.net>

Signed-off-by: Werner Koch <wk@gnupg.org>
---
 src/logging.c | 18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/src/logging.c b/src/logging.c
index 1a4f620..d01f974 100644
--- a/src/logging.c
+++ b/src/logging.c
@@ -1090,9 +1090,10 @@ _gpgrt_log_flush (void)
 
 
 /* Print a hexdump of (BUFFER,LENGTH).  With FMT passed as NULL print
- * just the raw dump, with FMT being an empty string, print a trailing
- * linefeed, otherwise print an entire debug line with the expanded
- * FMT followed by a possible wrapped hexdump and a final LF.  */
+ * just the raw dump (in this case ARG_PTR is not used), with FMT
+ * being an empty string, print a trailing linefeed, otherwise print
+ * an entire debug line with the expanded FMT followed by a possible
+ * wrapped hexdump and a final LF.  */
 void
 _gpgrt_logv_printhex (const void *buffer, size_t length,
                       const char *fmt, va_list arg_ptr)
@@ -1150,7 +1151,16 @@ _gpgrt_log_printhex (const void *buffer, size_t length,
       va_end (arg_ptr);
     }
   else
-    _gpgrt_logv_printhex (buffer, length, NULL, NULL);
+    {
+      /* va_list is not necessary a pointer and thus we can't use NULL
+       * because that would conflict with platforms using a straight
+       * struct for it (e.g. arm64).  We use a dummy variable instead;
+       * the static is a simple way zero it out so to not get
+       * complains about uninitialized use.  */
+      static va_list dummy_argptr;
+
+      _gpgrt_logv_printhex (buffer, length, NULL, dummy_argptr);
+    }
 }
 
 
-- 
2.8.0.rc3

